Medicine is providing ever-increasing demands for devices that can navigate narrow passageways to a desired location within a body so that diagnostic and therapeutic procedures can be performed at that location. Currently, elongated medical devices such as catheters can extend into a body from outside via an access point through various connected passageways to a target location. It is sometimes desirable to perform electrosurgical procedures at the target location.
An electrosurgical procedure involves a medical device having an electrode tip that is electrically energized to perform a procedure such as coagulation, dissection, desiccation and cautery. The electrical energy can be provided in either direct current (DC) form or in alternating current (AC) form. Low frequency electrical energy, including DC, can stimulate muscle and nerves and have potentially undesirable outcomes, such as cardiac arrest, if not properly handled. Higher frequency electrical energy, and in particular electrical energy in the radiofrequency (RF) range (e.g., about 3 kilohertz to about 300 gigahertz), may not stimulate muscle or nerves, and therefore may be better suited to core and coagulate tissue. An electrode tip energized by ultrasonic energy can also be used to perform electrosurgical procedures such as coagulation and tissue ablation.
Modern day elongated medical devices can provide percutaneous access to inner organs and other tissue, and can allow clinicians to navigate to remote and narrow locations within a body. To provide such percutaneous access, these elongated medical devices must meet a variety of requirements such as a desired length, a sufficiently small outer diameter to permit navigation to narrow body passageways, and sufficiently large inner diameter to permit delivery of the required functionality to the remote location. In the case of an elongated medical device having an RF-powered electrode tip, for example, the device can have an inner diameter sufficiently large to transfer the required energy to the electrode tip. To guide the electrode tip to the target site within a body, the elongated medical device including the electrode tip can be deployed into the body through a small trocar. The elongated medical device is advanced in the body to the target site in the body, and the electrode tip is energized at the target site to perform the electrosurgical procedure. An elongated delivery system (e.g., a delivery catheter and/or guidewire) can be used to guide the elongated medical device through the body to the target site.
Electrode tips delivering RF energy can be monopolar or bipolar. A monopolar tip includes one electrode, and a ground pad electrode is located on the patient. Energy applied through the electrode travels through the patient to ground, typically the ground pad. With a bipolar tip, the ground pad electrode located on the patient is eliminated and replaced with a second electrode pole as part of the tip. These active and return electrodes of a bipolar tip are typically positioned close together to ensure that, upon application of electrical energy, current flows directly from the active to the return electrode. Bipolar tips can be advantageous compared to monopolar tips because the return current path only minimally flows through the patient. In bipolar tips, both the active and return electrode are typically exposed so they may both contact tissue, thereby providing a return current path from the active to the return electrode through the tissue. Also, the depth of tissue penetration may be advantageously less with a bipolar tip than with a monopolar tip. Whether monopolar or bipolar, electrode tips made of rigid materials govern the size and shape of the electrode tip that can be deployed through a small trocar and through narrow passageways in the body. The size and shape of the electrode tip can affect the functionality and performance capabilities of the electrode tip at a remote surgical site in the body.